Not all biofuels are created equal: in fact, depending on how they are produced, biofuels like ethanol and biodiesel can be environmentally destructive, raise the price of food, and even hurt efforts to tackle global warming.

Biofuels - ethanol and biodiesel - present a potentially important (partial) solution to concerns about global warming and our over-reliance on oil. However, to paraphrase a great LA Times op ed on the ethanol craze, alcohol is best enjoyed in moderation, and the same goes for these alcohol-based biofuels.

So before we all get drunk on ethanol, we'd better take a close look at the benefits and potential drawbacks of biofuels and make sure we get it right.

The Benefits - In Pursuit of Energy Independence and a Safe Climate

Biofuels offer the potential to displace foreign oil and depleting fossil fuels with a more sustainable and domestic fuel while reducing greenhouse gas emissions.

Still, depending on how they are produced, ethanol and biodiesel require considerable fossil fuel inputs - diesel for tractors, natural gas for fertilizers, fuel to transport the feedstocks, and typically fossil fuels to produce the biofuels at a biorefinery. So while the biofuel itself may be made from renewable crops and contains only carbon that was absorbed from the atmosphere during the growth of the plants, the total net benefit of biofuels after taking into account inputs is far from carbon neutral nor fossil fuel free.Exactly how much net benefit there is to biofuels depends largely on the production methods and feedstocks and has been the subject of much debate. While some have repeatedly made the case that conventional biofuels - corn-based ethanol and soy or rapeseed-based biodiesel - take even more fossil fuels to produce than the offset, the consensus has been that conventional biofuels offer a moderate reduction in fossil energy use and greenhouse gas emissions - on the order of a 10-30% reduction when compared to conventional petroleum-based gasoline and diesel.

Next-generation biofuels produced from cellulosic feedstocks - a fancy term for a wide variety of generally inedible plant matter including wood, straw, and grasses as well as agricultural wastes like corn stalks and rice hulls - are an exciting prospect and could maximize the potential for biofuels to offset oil and fossil fuel use and greenhouse gas emissions.

Making ethanol or biodiesel from cellulosic feedstocks can be a much more energy efficient process than conventional corn or soy-based biofuels, can be made from inedible crops and even agriculture, forestry, or urban waste materials.

However, next-generation, cellulosic biofuels are currently in the early stages of commercialization. The first pilot and commercial scale cellulosic biofuel refineries are under construction or on the drawing boards these days and how long it will take to fully scale up and commercialize the emerging biofuel technology remains to be seen.

Up in Smoke - How Slash and Burn Agriculture Wipes Out the Climate Benefits of Biofuels

Land use changes - most notably the loss of tropical forests - account for about 20 percent of total global greenhouse gas emissions - roughly the same as both the total annual emissions from the United States or China.

That's right: slash and burn agriculture can be just as large a threat to the climate as China's rampantly growing economy or the hundreds of millions of cars plying American highways!

So if we're going to start replacing oil with biofuels, we'd better not be trading one problem - rampant oil consumption - for another equally devastating problem - accelerating the conversion of tropical rainforests into farm and grazing lands.

Slashing massive swaths of forests to clear the way for biofuel plantations clearly amounts to a devastating ecological loss. These tropical and semi-tropical forests are some of the most biologically-diverse habitats in the world and have already been devastated by traditional timber and agricultural demands. It's no wonder the Worldwatch Institute has called China's biofuels expansion "an ecological disaster," and the same can be said for similar biofuel expansion plans across the world.

But even beyond the massive loss of biodiversity and habitat when forests are converted to biofuel plantations, the destruction of these forestlands also wipes out any global warming benefits of biofuels.

When you destroy forestlands, grasslands, savannas and other wilderness, much of the carbon stored in the ecosystem's living matter ends up in the atmosphere - burned, decomposed or otherwise oxidized. Additionally, forestlands represent an important carbon sink, 'breathing' carbon dioxide out of the atmosphere and storing it as trees and other plants grow.

The loss of these important natural carbon 'scrubbers' more than makes up for the moderate reductions in greenhouse gas emissions from burning biofuels instead of gasoline or diesel: according to the study, it would take up to a century for the benefits of biofuels to recoup the initial loss of the tropical forestland and the emissions associated with slashing and burning the land to make way for biofuel plantations!

Furthermore, the study concludes that the climate benefits of biofuels are trumped by reforestation efforts, even in temperate climates. "You get far more carbon sequestered by planting forests than you avoid emissions by producing biofuels on the same land," says Righelato.

The study's authors found that reforestation would store and sequester between two and nine times as much carbon over 30 years than would be saved by burning biofuels produced on the same amount of land instead of gasoline (see bar chart below).

[Graphic: the carbon savings from burning biofuels instead of gasoline (top six bars) compared to the carbon emissions resulting from clearing tropical forestland for biofuel plantations (red bar) and the carbon savings from reforestation efforts (bottom three bars). Figures are expressed as metric tons of carbon equivalent saved or emitted per acre devoted to biofuel production or reforestation. (Source: New Scientist)]

No Free Lunch When Fuel Competes with Food

We all know the old adage: there's no such thing as a free lunch. Well, when fuel competes with food, everyone's lunch gets more expensive (as the LA Times accurately observes).

The vast bulk of global biofuels production utilizes edible feedstocks like corn and soy. As demand for corn to make ethanol has soared, corn prices have shot up, nearly doubling in the past year. Record high prices are encouraging a record acreage of corn planted in the United States - the highest in 63 years - and prices for other foods are on the rise as farmers plant corn in acreage they have otherwise planted wheat or soy.

Prices for all kinds of food have soared in the first half of 2007 (see chart below) and the LA Times op ed reports that grocery-store food prices rose 8%. It's unknown how much of that hike is attributable to corn, and rising fuel and fertilizer costs are certainly a major factor in rising food prices, but soaring demand for corn for ethanol production is certainly playing a significant role as well.

Middle class Americans may be able to shrug off higher prices at the grocery store, but increasing food costs hit lower income folks harder.

And if low-income Americans are feeling the crunch, things are even harder in the developing world. When you get buy on just a few dollars a day, doubling corn prices are no small matter. Rising corn prices have already launched public outcry and even riots in Mexico, which depends on imported American corn for tortillas and other affordable, nutritious stables.

Producing biofuels from inedible cellulosic feedstocks could provide a solution to this fuel-or-food dilemma, although producing energy crops like switchgrass - an excellent biofuel feedstock and native North American grass that once dominated much of the Great Plains - on limited agricultural land could continue the competition between biofuels and foodstuffs.

Clean Green Fuels? - Other Environmental Effects

Industrial farming to produce biofuel feedstocks, particularly corn, consumes large amounts of water and chemical fertilizers, herbicides and pesticides. Many of these chemicals seep into waterways, polluting the water and providing nutrients for algae blooms that suck up all the oxygen and kill everything else. A 'dead zone' the size of Connecticut and Delaware put together has repeatedly formed in the Gulf of Mexico, caused by algae gorging on chemical fertilizers carried into the Gulf by the Mississippi river.

Additionally, farmers ordinarily rotate crops annually to avoid soil exhaustion, but high corn prices encourage them to plant corn in the same fields year after year. This high-intensity farming accelerates the loss of topsoil and depletes soil nutrients and the only way to make this work is to pour on more fertilizers, further exacerbating problems.

Finally, while ethanol may be "cleaner burning" when it comes to many pollutants and is a better fuel additive or "oxygenate" than toxic MTBE, burning ethanol in high concentrations could increase certain air pollutants. A recent Stanford University study argued that E85 - a blend of 85% ethanol and 15% gasoline - produces so much ozone, a key ingredient in smog, that if it were used in Los Angeles instead of gasoline, it would raise ozone-related deaths 9%.

Don't Throw the Baby Out With the Bathwater - If We're Smart, Biofuels Still Have a Role to Play

Given all of these concerns about increased use of ethanol and biodiesel, should we just bag the whole idea and move on to something else? No, I would argue.

When it comes to confronting the climate crisis and ending our oil addiction - two massive problems - we're going to need all the tools we can get. Biofuels, if done right, still have an important role to play in reducing our reliance on oil and our contribution to global climate change.

I present the above concerns about biofuels because understanding the potential pitfalls, problems and limitations of biofuels - both conventional and next-generation - will be crucial to developing the standards that are necessary to ensure that biofuels can help make a dent in our oil addiction and help solve the climate crisis without exacerbating other environmental problems.

These feedstocks offer the least environmental impacts, do not compete with food crops, and according to this study (pdf) are available in large enough quantities to be worth pursuing - roughly 3/4 of a billion dry tons each year, or enough to produce around 75 billion gallons of ethanol or biodiesel if estimated yields from next-generation biorefineries prove correct.

That is enough biofuel to provide about 1/3rd of all the energy consumed by cars and light trucks in the United States.

Additionally, unlike producing ethanol from corn, which typically requires large amounts of coal or natural gas, converting cellulosic biomass to biofuels requires little or no fossil fuel inputs. In fact, cellulosic biorefineries should be able to utilize the lignin portion of the biomass left over after the cellulose is removed to produce all of the energy inputs for the refinery process and even produce electricity for export (potentially offsetting electricity from coal or natural gas).

Getting on the Right Path - Time for a New U.S. Biofuels Strategy

To be done right:

Biofuels should not come from edible feedstocks, including corn, soy or wheat.

Biofuels should preferably be produced from readily-available, existing waste streams of cellulosic biomass.

If produced from an energy crop, sustainable harvesting practices should be employed, the crops should be grown on existing farmland and should be planted as part of a regular, sustainable crop rotation so as to not compete with foodstuffs.

The full, lifecycle greenhouse gas emissions of all biofuels should be considered, including (and especially) emissions from land use changes. Under no circumstances should a biofuel feedstock be utilized that results in the clearing of rainforest or other wilderness areas or results in a net increase in greenhouse gas emissions.

Employing these kinds of standards in our public policy would necessitate a dramatic shift away from heavily supporting corn-based ethanol and soy-based biodiesel.

It would necessitate the creation of environmental sustainability standards for the U.S. biofuels industry and would imply a ban on imported biofuels from countries that do not adopt satisfactory sustainability standards on their own domestic biofuels industries.

It would require a focus on commercializing next-generation cellulosic biofuel technologies and exploring the most sustainable feedstock sources and harvesting/collection methods.

So, given all of the concerns about biofuels, why aren't any of our elected officials calling for a change in direction for the U.S. biofuels industry? Why do we continue to subsidize the corn ethanol industry to the tune of several billion dollars a year? Why do all of the presidential candidates pay at least lip service to corn ethanol, even those like Hillary Clinton and John McCain that have been openly critical of corn ethanol in the past?

Well, the political power of agri-giants like ADM and Cargill and the importance of corn-growing Iowa in presidential elections are certainly standing in the way of a sensible biofuels policy. It's hard to find another explanation for an energy policy that is so clearly designed to do little to actually solve any of the problems it's supposed to solve while so clearly benefiting narrow but politically powerful special interests.

The latest Senate energy bill continues this trend with a massive 36 billion gallon/year by 2022 biofuels requirement, 40% of which will likely come from good old corn-based ethanol, necessitating a quadrupling in the U.S. corn ethanol industry! (To be fair, the bill does require that 60% of the standard is met with next generation biofuels...)

It's time for a change in American energy policy when it comes to biofuels. It's time to actually have an energy policy when it comes to biofuels, and not a massive agricultural subsidy program disguised as an energy policy.

Let's heed the warnings of climate scientists, ecologists and rioting Mexican peasants: the path we're on right now means biofuels exacerbate the climate crisis, amount to an environmental disaster, and drive up prices for food around the world.

But there's another path, a path where sustainably-harvested, next-generation biofuels coupled with a dramatic increase in fuel efficiency and the adoption of plug-in hybrid electric vehicles makes gasoline a thing of the past.

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